Integrated circuits that provide protection against high voltage, such as electrostatic discharge, for example, are generally configured so that at least one of transistors making up a voltage-dividing resistance in the protecting circuit is short-circuited in response to abnormal high voltage applied between power-supply conductors (as in, for example, Japanese Patent Application JP-H07-321628 A). This integrated circuit provides a hysteresis effect to current flowing through the protecting circuit with respect to the voltage applied.
To protect a circuit (hereinafter called a protected circuit) against high voltage, a protecting circuit may be required to discharge a predetermined value of current between the power supply voltage supplied to the protected circuit and breakdown voltage of the protected circuit when the high voltage is applied thereto.
Recently, the difference between the power supply voltage and the breakdown voltage of a protected circuit tends to decrease. However, when a difference in voltage between the power supply voltage and the breakdown voltage of a protected circuit is small, this may lead to difficulty in discharging a predetermined value of current when high voltage is applied thereto.